Readout of the ATLAS Liquid Argon Calorimeters John Parsons Nevis Labs, Columbia University Representing the ATLAS LAr Collaboration ATLAS

J. Parsons, Siena, October 2002 LHC : pp √s = 14 TeV Design Luminosity : cm -2 s -1 Liquid Argon Calorimeters Barrel EM ~ channels End Cap EM ~ HEC ~ 5888 FCAL ~ 3584 In total ~ 190 K channels

J. Parsons, Siena, October 2002 read out  190k channels of calorimeter dynamic range  16 bits measure signals at bunch crossing frequency of 40 MHz (ie. every 25 ns) store signals during L1 trigger latency of up to 2.5  s (100 bunch crossings) digitize and read out 5 samples/channel at a max. L1 rate of 100 kHz measure deposited energies with resolution < 0.25% measure times of energy depositions with resolution << 25 ns high density (128 channels per board) low power (  0.8 W/channel) high reliability over expected lifetime of > 10 years must tolerate expected radiation levels (10 yrs LHC, no safety factors) of: TID 5 kRad NIEL 1.6E12 n/cm2 (1 MeV eq.) SEU 7.7E11 h/cm2 (> 20 MeV) Requirements of ATLAS LAr Frontend Crate Electronics

J. Parsons, Siena, October 2002 Overview of ATLAS Liquid Argon (LAr) Calorimeter Readout

J. Parsons, Siena, October 2002 ATLAS LAr Frontend Crate Electronics Overview On-detector electronics Boards tested functionally on Mod 0 ATLAS rad-tol boards being finalized Calibration : ch Front End Board (FEB) : ch Controller : 116 boards Tower builder (TBB) : ch

J. Parsons, Siena, October 2002 Approx channels of full functionality “Module 0” boards were developed and produced 50 FEB, 12 calib, 2 TBB Provided verification of electronics design concepts Have been operating reliably in testbeam runs with Module 0 and production calorimeter runs at CERN for past several years Performance meets or exceed ATLAS specifications (for sample results, see other ATLAS LAr talks at this conference) Due to schedule, Mod 0 electronics were developed without requiring radiation tolerance the main task remaining in the development of the final ATLAS boards was to radiation harden the designs, and in particular to replace several FPGAs and other COTs with custom rad-tol ICs Module 0 Electronics Experience

J. Parsons, Siena, October 2002 Over 10 yrs at design luminosity, on-detector electronics must tolerate significant exposure to ionizing rad’n, neutrons, and other hadrons TID 5 kRad NIEL 1.6E12 n/cm2 (1 MeV eq.) SEU 7.7E11 h/cm2 (> 20 MeV) Rad’n qualification requires extensive testing of components, including large SAFETY FACTORS due to uncertainties in simulation, possible low dose rate effects, and possible lot-to-lot variations Combined safety factors can be as high as 70 (!!) In addition to total damage, need to pay careful attention to possible single event upsets (SEU) of digital logic Radiation Tolerance Requirements Barrel FEC Endcap FEC

J. Parsons, Siena, October 2002 Reduce/avoid use of COTs Developed 12 different custom ASICs using specialized rad-tol processes: 9 DMILL chips 3 DSM chips (using rad-tol standard cell library) Paid careful attention in ASIC design to “harden” design against SEU. Triple-redundancy and majority voting techniques for critical registers Parameter storage with Hamming code and EDC logic eg. DSM SCA Controller reduces req’d FEB Reset rate by factor ~ 70 (residual rate < 1 FEB/hr in whole system) Radiation qualification process requires TESTING, TESTING, TESTING!! Radiation Hardening the ATLAS LAr Readout

J. Parsons, Siena, October 2002 Provide redundant optical links to off-detector control electronics for TTC (trigger/timing) and SPAC (serial control for downloading/reading back configuration parameters) Provide (bussed) SPAC and (point-to-point) TTC signals to rest of boards in ½ crate Prototype being developed now; to be delivered end Oct. for beginning of set up of system crate test Controller Board Overview

J. Parsons, Siena, October 2002 Generate 0.1% precision calibration pulses Rise time < 1 ns Current pulse amplitude from 200 nA up to 10 mA Delay programmable from 0 to 24 ns in 1 ns steps Number of current pulsers per CALIB board is 128 Calibration Board Overview

J. Parsons, Siena, October 2002 Overview of Main CALIB Components 128 Output signals 1 TTCRx 4 pos. Vreg and 1 (non-essential?) neg. Vreg 128 opamp 10 μV offset 6 CALogic 1 SPAC 5 Ώ 0.1% 50 Ώ 0.1% 10 uH 128 HF switch 2 delay 16 driver 1 DAC 16 bits V DAC Enable CMD I DAC Spac TTC DMILLAMSCOTS

J. Parsons, Siena, October Channel CALIB Prototype Include digital control plus analog chain for 8 channels 3 boards received in April 02 Design of full-sized 128 channel board is underway; delivery by Nov. Opamps & switch DAC CALlogic TTCRx Delay SPAC2 8 outputs

J. Parsons, Siena, October 2002 functionality includes: receive input signals from calorimeter amplify and shape them store signals in analog form using SCA while awaiting L1 trigger digitize signals for triggered events transmit output data bit-serially over optical link off detector provide analog sums to L1 trigger sum tree Frontend Board Overview

J. Parsons, Siena, October 2002 SCA Analog Memory Provides analog signal storage during L1 latency of up to 2.5  s (100 bunch crossings) 144 cell pipeline, to give multi-event derandomizing buffer Design developed in rad-soft technology, and then successfully migrated to rad-hard DMILL version Some performance numbers: Signal range3.8V Noise 300  V Fixed Pattern Noise 190  V DC Dynamic range13.3 bits Cell-to-Cell DC gain spread < 0.02% Chan-to-chan offset spread10mV RMS Voltage droop< 3mV/ms To automatically test > SCA chips, a robotic test station was developed SCA tests underway (yield ~ 70%); finish by end 2002 Same setup already used to test > Shaper chips

J. Parsons, Siena, October different custom rad-tol ASICs, relatively few COTs Overview of main FEB components 32 SCA16 ADC8 GainSel 1 GLink1 Config.2 SCAC 1 SPAC 1 MUX 32 Shaper 1 TTCRx 7 CLKFO 14 pos. Vregs +6 neg. Vregs 2 LSB 32 0T 128 input signals 1 fiber to ROD Analog sums to TBB DMILL DSM AMS COTS 2 DCU TTC, SPAC signals

J. Parsons, Siena, October channels/FEB components on both sides to achieve density Need neg. Vregs before launching 20 FEB pre-production for system crate test, last major milestone before beginning production FEB Prototype Shapers SCAs ADCs O/P optical link SPAC Preamps GainSel SCA Controllers TTCRx 128 I/P signals

J. Parsons, Siena, October 2002 one GLink output link per FEB, with rate of 1.6 Gbps  Total raw data rate from 1524 LAr FEBs  2.4 Tera bps FEB Optical Links 1.6 Gb/s

J. Parsons, Siena, October 2002 Overview of ATLAS Liquid Argon (LAr) Calorimeter Readout

J. Parsons, Siena, October 2002 Readout Driver (ROD) Overview Process raw data in real 100 kHz L1 rate: Apply calibration constants From 5 time samples per channel, calculate (via optimal filtering): Deposited energy Time of energy deposition Pulseshape quality (  2 ) Format processed data and transmit to L2/DAQ Perform histogramming + monitoring of raw data ROD Demo program allowed successful prototyping of several different commercial DSPs selected 600 MHz TI 6414 ROD prototype being finalized DSP on plug-in daughter board allows “staging” of ROD system for initial running (at lower L1 rate) by originally producing only 50% of the processing power

J. Parsons, Siena, October 2002 Some 6414 ROD Demonstrator Results 600 MHz TI 6414 can process 128 channels (one FEB) in less than 10  s Independent DMAs for I/P and O/P streams provide enough I/O bandwidth without significant impact on processing DSP memory sufficient to store “reasonable” set of histo’s Due to 6414 cache structure, simulator gives overly optimistic results Design of final Double Processing Unit (PU) with two 6414 DSPs, and of ROD Motherboard incorporating 4 Double PUs, is underway Prototypes should be available in early 2003

J. Parsons, Siena, October 2002 Summary Radiation hardening the Module 0 electronics designs has required a VERY significant effort over several years development of a large number of custom ASICs extensive irradiation test programs for both custom ASICs and COTs All components are in, or will move into, production by the end of 2002 Final prototypes of all front end electronics boards will be available by the end of 2002 We have suffered a significant delay due to continued problems in the development of rad-tol negative Vregs (hopefully resolved very soon) During 2003, a “system crate test” of ~2500 channels will be performed, as the last remaining major milestone before moving to production Prototypes of ROD and other off-detector electronics will be available by Spring 2003 Testbeam in 2004 could provide operating experience with final electronics Final electronics installation in ATLAS pit scheduled to begin Nov. 2004